Liquid stabilizers for vinyl chloride resins comprising metal salts of epoxidized fatty acids



3,297,584 Patented Jan. 10, 1967 Fice 4 Claims. (51. 252-4410 The present invention is concerned with liquid stabilizers for polyvinyl chloride and polyvinyl chloride mixed polymers and with a process for the production of said stabilizers.

Synthetic halogen-containing resins, particularly polyvinyl chlorides and mixed polymerizates thereof, are stabilised with, inter alia, metal soap combinations based on cadmium, zinc and barium. These stabilizers are powders or plastics, according to the nature of the carboxylic acid used.

Powdery products, which also good lubricants, general ly contain C to C straight chained fatty acids. For some fields of application, for example in combination with plastisols, liquid polyvinyl chloride stabilizers, i.e. solutions of metal soaps in solvents, are preferred which can be produced in a more pure form than powdery metal soaps. For reasons of effectiveness, the metal soap solutions must be as highly concentrated as possible.

For the dissolving of the metal soaps, solvents must be used which are compatible with the synthetic resins. Generally, plasticizers are used for this purpose. However, metal soaps of straight chained fatty acids only dissolve very slightly in organic solvents and solutions of this type solidity, even with a small percentage content of metal soap, to give solid gels. Thus, for example, barium and cadmium stearates are only soluble in dibutyl phthalate to about 0.5%. Therefore, they cannot be used for the production of liquid polyvinyl chloride stabilizer compositions with a high metal soap content. For this reason, in the case of known liquid barium-cadmium stabilizers for polyvinyl chloride, there are used as organic components, in place of the straight chained fatty acids with 820 carbon atoms, branched, short chained aliphatic carboxylic acids, such as ethyl-hexanoic acid, or phenols.

However, these organic components, in contradistinction to the metallic salts of fatty acids, do not give the polyvinyl chloride mixtures any lubrication properties so that additional lubricants must be employed. Because of the limited compatability of these metallic salts with polyvinyl chloride, the amount in which they may be added is limited.

We have now found that the solubility of barium, zinc and cadmium salts of straight chained fatty acids in organic solvents can be very considerably increased by the introduction of epoxy groups into the fatty acid molecule. The dependence of the viscosity on the amount of cadmium epoxy stearate dissolved in dibutyl phthalate, with the addition of 1.25% triethanolamine, is illustrated in FIGURE 1 of the accompanying drawings. If the organic components of the barium-cadmium metal salts contain, in addition to the epoxy group, a hydroxyl group,

duced, for example, from epoxidized unsaturated fatty acids, their esters and glycerides. As fatty acid basis there may be used the naturally-occurring unsaturated oils which contain, in the main, oleic acid, linoleic acid, linolenic acid or ricinoleic" acid. The metal soap solutions according to the present invention can contain single metal salts of the epoxidized unsaturated fatty acids or several such salts in combination with one another.

The preferred metal soaps of epoxy fatty acids are those of epoxy-stearic acid, diepoxy-stearic acid, hydroxyepoxy-stearic acid and mixtures thereof.

As solvents for the metallic soaps of straight chained epoxidized fatty acids there are used those liquid organic compounds which are compatible with halogen-containing synthetic resins but which, however, preferably also act as plasticizers for the resins and increase the stabilizing effect of the barium-zinc-cadmium soaps.

The solubility of the metallic soaps is dependent upon the metallic component and on the epoxy fatty acid used. In general, the cadmium and zinc soaps are more easily soluble than the barium salts.

The best solvent properties are shown by phosphite plasticizers, such as phosphorous acid esters, especially triphenyl phosphite, phthalic acid esters with short chained alcohols, such as dibutyl phthalate, epoxy plasticizers, such as epoxy castor oil, and esters of ricinoleic acid with aliphatic long chained alcohols. Furthermore, alkyl-phenols, such as Z-isopropyl-phenol, 2-methyl-4-tertiary-butylphenol and 2,4-dimethyl-phenol, have a very strong solubilising action on the metallic salts of epoxidized straight chained fatty acids.

For increasing the concentration of the metal soaps in the solutions and for the reduction of their viscosity, gelbreaking additives, such as polar organic compounds, for example alkanolamines, especially triethanolamine, alcohols, phenols or aliphatic polyhydroxy compounds, can be used. The phosphite plasticizers also show gel-breaking properties.

We have also found that the combination of barium, zinc and cadmium soap are less viscous than solutions containing the same percentage of the individual components. By such a combination, a larger amount of metal soap can thus be brought into solution at any given viscosity.

In the case of using a combination of barium, zinc and cadmium soaps, one or two metallic soap components can consist of a known metallic soap which is soluble in organic solvents compatible with polyvinyl chloride. As such a combination there may be mentioned the barium soap of epoxidized ricinoleic acid-cadmium octoate. This possibility can be of significance when the metal content is to be increased Without an increase of the lubrication properties being necessary. As a result of their very good solubility, the barium soaps of epoxidized ricinoleic acid offer a particularly good combination possibility.

The barium-zinc-cadmium-epoxy metal soaps can be dissolved to give liquid stable solutions having a concenand 100 C. suffices. The solutions are then freed by filtration, for example at an elevated temperature, from In general, a temperature between the undissolved components which are present as impurities in the starting materials, such as metallic hydroxides or metallic carbonates.

In so far as the solvents used are gel-breaking substances, which alone or in combination with metallic stabilizers possess stabilizing properties, such as, for example, in the case of epoxy plasticizers, phosphite plasticizers and alkyl phenols, the ratio of the individual components to one another in the composition is determined by their synergistic effectiveness. Therefore, for the composition of a liquid composition of stabilizers the maximal effective ratio of the individual components to one another is determined and then, by the addition of a suitable solvent, particularly of a plasticizer, the desired viscosity adjusted. In the case of the combination of two efiective stabilizers, the maximal ratio can be easily read ofl? from a graphic representation. In the case of combinations of three active stabilizers, the evaluation takes place in the form of a phase diagram. In the case of more than three active stabilizers, it is recommended to keep constant one of the components for the graphic evaluation of the results.

FIGURE 2 of the accompanying drawings serves to show how particularly elfective mixtures of three active stabilizers can be ascertained. As an example, the threecomponent combination cadmium-epoxy-hydroxy-stearate, p-tertiary-octyl-phenol and epoxidized castor oil is investigated. The numbers 2 and 1 in the corners and in the middle of the diagram signify the amounts of the materials in question. For every mixture ratio Within the ternary diagram, the static stability at 180 C. is deter mined in an oven for a mixture of 100 parts polyvinyl chloride, 50 parts dioctyl-phthalate and 2 parts of stabilizer. The production and examination of the mixtures take place in the same manner as is described in the following examples. At intervals of 10 minutes, test samples are taken from the oven and the time determined after which the original color of the mixture has changed to yellow-brown. These times are incorporated into the ternary diagram. Points of the same time are joined by broken lines. From FIGURE 2 of the accompanying drawings can be read off which ternary stabilizer mixture has the maximum effectiveness. The marginal conditions also show whether binary stabilizer mixtures can be used with advantage.

The system illustrated in FIGURE 2 of the accompanying drawings has a double maximum at 1.6 parts cadmium soap of epoxidized castor oil and 0.4 part ptertiary-octyl phenol. The maximum of the tertiary system lies at 0.25 part p-tertiary octyl phenol, 0.7 part cadmium soap of epoxidized ricinoleic acid and 1.05 parts epoxidized castor oil.

The following examples serve for the illustration of the production of the metal soap solutions and their effectiveness is polyvinyl chloride masses, the parts given being parts by weight.

The metal soap solutions are produced in the following manner: The solid components are cold pasted with a little solvent and slowly heated with stirring. At about 80-90 C., the remaining amount of liquid is added portionwise and further heated until complete solution is obtained. In Example 1 the temperature must not exceed 140 C. and in Examples 2-4 must not exceed 90-100 C. since, otherwise, unnecessary colorations occurs. In all cases, the color of the solutions is yellow to yellow-brown. For the removal of non-dissolved components, such as metallic hydroxides, carbonates and the like, the solution is filtered at about 50 C. through a fine mesh sieve.

Example 1 9.9 parts p-tertiary-octyl-phenol, 27.4 parts cadmium soap from epoxidized castor oil, 42 parts epoxidized castor oil, 19.8 parts dibutyl phthalate and 0.9 part triethanolamine.

f 4 Example 2 6 parts cadmium epoxystearate, 4 parts barium epoxystearate, 10 parts 2,4-dimethylphenol and 2 parts triphenyl phosphite.

Example 3 8 parts cadmium epoxystearate, 10 parts 2,4-dimethylphenol and 2 parts triphenyl phosphite.

Example 4 (a) 6 parts cadmium soap of epoxidized castor oil, 4 parts barium soap of epoxidized castor oil, 10 parts of mixed 2,4- and 2,5-dimethylphenol and 2 parts of triphenyl phosphite.

(b) 6 parts cadmium octoate, 4 parts barium epoxystearate, 10 parts 2,4-dimethylphenol and 2 parts triphenyl phosphite.

Example 5 20 parts zinc epoxystearate, 20 parts 2,4- and 2,5-dimethylphenol and 5 parts triphenyl phosphite.

2 parts of the liquid stabilizer combinations of Examples 1-4 and a combination consisting of 0.5 part of the stabilizer combination of Example 5 and 1.5 parts of the stabilizer combination according to Example 2 are worked up into and plasticized with a test mixture consisting of parts of a suspension of polyvinyl chloride (K-value 70) and 100 parts dioctyl phthalate, within a period of 10 minutes, in a mixing roller mill at C., then drawn out into foils and individual test pieces heat dried in a drying oven with normal air movement at C. By the removal of test pieces at intervals of 10 minutes, the time was determined after which a change of appearance from colorless to yellow brown occurs. In all the examples, the coloration occurs after 70 minutes. The same mixtures were subjected to a continuous rolling in a roller mill, the rollers rotating at the same speed, at 170 C. and by removal of test pieces at intervals of 10 minutes, the time was determined at which adhesion to the rollers or a coloration occurred. The time until the adhesion to the rollers is regarded as a measure for the lubrication property of the mixture.

The continuous rolling of the mixtures produced from the examples showed the following values:

Continuous roller milling The low lubrication properties of the metal soaps of epoxidized castor oil acids is particularly noticeable this being accentuated by the influence of the hydroxyl group.

What is claimed is:

1. Liquid stabilizers for polymeric and copolymeric vinyl chloride comprising a solution containing 40 to 60 wt. percent of at least one member selected from the group consisting of barium, zinc, and cadmium soaps of epoxy stearic acid, diepoxy stearic acid, and hydroxy epoxy stearic acid in an organic solvent capable of simultaneously serving as a plasticizer and/or stabilizer for said polymeric vinyl chloride selected from the group consisting of alkyl monohydric phenols, esters of phthalic acid with short-chain aliphatic alcohols, substahtially neutral esters of phosphorous acid (H PO epoxidized castor oil, and esters of ricinoleic acid with aliphatic long chain alcohols prepared by heating a mixture of said soap group member and said organic solvent group mem' References Cited by the Examiner UNITED STATES PATENTS 1,932,889 19/1933 Groff 26045.9 2,564,646

8/1951 Leistner et a1 26045.7

6 Greenspan et a1 260--23 Lally 260-45.95 Myers et al. 26045.95 Leistner et a1 26045.7

FOREIGN PATENTS 7/1960 Great Britain.

LEON I. BERCOVITZ, Primary Examiner.

MILTON STERMAN, Examiner.

R. A. WHITE, T. D. KERWIN, Assistant Examiners. 

1. LIQUID STABILIZERS FOR POLYMERIC AND COPOLYMERIC VINYL CHLORIDE COMPRISING A SOLUTION CONTAINING 40 TO 60 WT. PERCENT OF AT LEAST ONE MEMBER SELECTED FROM THE GROUP CONSISTING OF BARIUM, ZINC, AND CADMIUM SOAPS OF EPOXY STEARIC ACID, DIEPOXY STEARIC ACID, AND HYDROXY EPOXY STEARIC ACID IN AN ORGANIC SOLVENT CAPABLE OF SIMULTANEOUSLY SERVING AS A PLASTICIZER AND/OR STABILIZER FOR SAID POLYMERIC VINYL CHLORIDE SELECTED FROM THE GROUP CONSISTING OF ALKYL MONOHYDRIC PHENOLS, ESTERS OF PHTHALIC ACID WITH SHORT-CHAIN ALIPHATIC ALCOHOLS, SUBSTANTIALLY NEUTRAL ESTERS OF PHOSPHOROUS ACID (H3PO3), EPOXIDIZED CASTOR OIL, AND ESTERS OF RICINOLEIC ACID WITH ALIPHATIC LONG CHAIN ALCOHOLS PREPARED BY HEATING A MIXTURE OF SAID SOAP GROUP MEMBER AND SAID ORGANIC SOLVENT GROUP MEMBER AT A TEMPERATURE OF FROM 80 TO 140*C. 